Tess Vigeland: Every year our gadgets get cheaper, more sophisticated, faster and easier to use. It's the way the high tech economy works. And now it's working to put sophisticated and powerful intelligence tools typically used by professionals in the hands of average people like you and me -- and at RadioShack prices.

And Eric Butler fits right in. He's the creator of Firesheep. It's a browser plug-in that makes hacking so easy, even my mom could do it.

Eric Butler: Basically all you have to do is click a big start button and it will start listening on the network.

Pictures and names pop up on a bar along the left-hand side of the browser -- and anyone surfing the same wireless network you're on is suddenly vulnerable.

Butler: For example, Facebook. Firesheep will display the name and show the picture of other people in the room who are using that site. And if you double-click on that person, it will allow you to actually log-in as them.

You could send messages to their ex. Post photos -- do anything you want.

Firesheep's been downloaded more than 1.3 million times. Butler says he wrote it to make a point about how vulnerable we all are. Now he's building a smartphone app that will let users read trip data off strangers' transit cards -- right through their wallets.

Paul Saffo is a futurist and a managing director at Discern Analytics.

Paul Saffo: We worry about Big Brother. And this world of ubiquitous sensors and geo-location and augmented reality is wonderful stuff for Big Brother. The real surprise is that it enables Little Brother.

Consider a company called Flexispy. It lets customers surreptitiously load its software onto the phones of their frenemies, acquaintances or family members. Then starts spying, listening in on conversations -- even track people with GPS. And if that's too much trouble, you can buy your own malicious cell phone tower.

Don Bailey: So that you can intercept the voice transmissions, SMS, even data.

That's Don Bailey, a security consultant at iSec Partners.

Bailey: It used to cost tens of thousands of dollars -- but no longer. Today you can pick one up for about $1,200.

And all sorts of other technologies that were recently the provenance of spy agencies are becoming commonplace. Facial recognition, drones and tiny sensors have become toys. Jason Mitura's the chief technology officer at a Palo Alto start-up called Viewdle.

Jason Mitura: If you look historically, visual analysis, facial recognition has been kind of a super computer function that's only done on servers.

Mitura: We;rre not going to help you recognize people you don't already know. We are not going into the, "hold it up to a random stranger at a bar and find out who they are."

But Ryan Calo, the director of the Consumer Privacy Project at Stanford Law School, says as these technologies become more common -- and affordable -- abuse is almost inevitable.

Ryan Calo: I can tell you that there will be use cases that will bother you.

He says imagine for a second you're the editor of a tabloid -- or a suspicious spouse.

Calo: Why wouldn't you want to have a drone that flew around L.A. looking for Brad Pitt?

Or your cheating spouse?

Calo: If you have facial recognition technology and you have a drone with autonomous functioning.

Calo's serious. There is a two-foot wide drone on the market today you can buy for a couple hundred dollars. It can record streaming video and send it to your phone.

In fact, I own one. And a little while ago, Calo and I took it out for a test flight on Stanford's campus. But before we could gun the engines and start shooting video of random law students, we had to click through the disclaimer.

Calo: Obey all laws and respect the privacy of others. That's great. OK, no problem then.

Henn: That's right, we are all covered. It's all good.

In Silicon Valley, I'm Steve Henn for Marketplace Money.

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Steve Henn was Marketplace’s technology and innovation reporter until December 2011. He filed stories for the entire Marketplace portfolio. In addition, Henn occasionally acted as the back-up host for Marketplace Tech Report.